Vehicular Latch Assembly Pop-off Sound Reduction
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Solution Overview
Problem
Current closure latch assemblies in motor vehicles generate a pop-off sound due to the quick release of seal loads during power release operations, which increases the forces required for latch release and affects the size and power needs of the electric actuator, while also causing noise.
Innovation Solution
A closure latch assembly with a ratchet/pawl type mechanism and a pop-off sound reduction mechanism that includes an auxiliary pawl and striker lever, which applies a resistive force to counteract seal loads, reducing the exit velocity and acceleration of the striker, thereby minimizing the pop-off sound.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the compressive clamping force applied to the weather seals is increased to improve noise reduction, then the seal performance and wind noise reduction are improved, but the forces required to release the latch mechanism are increased and the electric actuator size and power requirements increase
Solution Approach 1:
The latch release process is segmented into multiple phases: initial pawl disengagement, intermediate controlled release phase with auxiliary pawl engagement, and final ratchet release. This segmentation allows the seal load to be managed in stages rather than released all at once, reducing the peak force requirement on the electric actuator while maintaining effective sealing.
Solution Approach 2:
The auxiliary pawl acts as an intermediary element between the main pawl and the ratchet mechanism. During the transition phase, the auxiliary pawl engages the ratchet to provide controlled resistance, mediating the release of seal loads and preventing sudden force spikes that would require a larger actuator.
2Object-affected harmful factors
If the compressive clamping force applied to the weather seals is increased to improve noise reduction, then the seal performance is improved, but the electric actuator size and power requirements increase
Solution Approach 1:
The power consumption is segmented across different phases of the latch operation. The electric actuator only needs to provide high power during the initial pawl disengagement phase, while the auxiliary pawl and spring mechanism handle the majority of the release process, significantly reducing the overall power requirement compared to a direct release system.
Solution Approach 2:
The latch release utilizes periodic action through the oscillating engagement and disengagement of the pawls with the ratchet teeth. This periodic mechanical action, driven by the spring mechanism, converts the stored elastic energy into controlled motion, reducing the continuous power demand on the electric actuator.
3Speed
If the seal loads are quickly released during power release operation, then the latch release speed is improved, but an audible pop-off sound is generated
Solution Approach 1:
The seal load release is segmented into multiple controlled steps through the sequential engagement and disengagement of the pawls with ratchet teeth. This stepwise release prevents the sudden, single-step release that causes pop-off sounds, while still maintaining a relatively fast overall release speed.
Solution Approach 2:
The auxiliary pawl and spring mechanism provide beforehand cushioning by being pre-positioned to engage the ratchet during the release process. This cushioning effect absorbs and dampens the impact forces that would otherwise generate audible pop-off sounds, while still allowing rapid release.
4Reliability
If a ratchet and pawl mechanism is used to retain the striker, then the latch reliability is improved, but the device complexity increases
Solution Approach 1:
The latch mechanism is segmented into functional modules: the primary ratchet and pawl for main retention, the auxiliary pawl for controlled release, the spring mechanism for energy storage, and the striker lever for actuation. This modular segmentation makes the complex system more manageable, easier to manufacture, and simpler to maintain while preserving reliability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively reduces the pop-off sound and the forces required for latch release, enhancing the operational efficiency and comfort by minimizing the seal loads exerted on the latch mechanism.
Implementation Method 1
an auxiliary pawl and striker lever, which applies a resistive force to counteract seal loads
Data Source
AI summary
A closure latch assembly for use in a motor vehicle closure system for releasably latching a vehicle door to a vehicle body. The closure latch assembly includes a latch mechanism providing a pop-off sound reduction function.